//
// Created by Administrator on 2025/9/4.
//
#include <set>

#include "../material/Sales_data.h"
bool compareIsbn(const Sales_data& lhs, const Sales_data& rhs)
{
    return lhs.isbn() < rhs.isbn();
}

int main()
{
    // bookstore can have several transactions with the same ISBN
    // elements in bookstore will be in ISBN order
    std::multiset<Sales_data, bool (*)(const Sales_data&, const Sales_data&)>
        bookstore(compareIsbn);
}
